This invention relates to trench shoring assemblies and, in particular to a type of trench shoring assembly known as a trench box which has a main frame.
A trench box is a type of trench shoring assembly used in excavation work when pipe is being laid. A typical trench box has two side walls spaced apart a fixed distance from each other by a plurality of spreader devices affixed to and perpendicular to each side wall. A fully assembled trench box is positioned in an excavated hole or trench and pipe is laid within a trench box, and after each length of pipe is laid the trench box is moved along the trench for laying the next length of pipe. The side walls keep the excavation area free from earth which may fall or cave into the excavated hole or trench before or during laying of the pipe.
Spreader devices are attached to the side walls in a variety of ways. One way which has been employed is to attach the spreader pipe to the inner skin or plate of a side wall. However, when this is done, any relative movement between the spreader devices and the side walls results in a sheering force between the spreader devices and the side walls. This sheering force, if great enough, will dislodge the spreader devices from the side walls thereby necessitating costly repairs to reattach the spreader devices to the wide walls and to repair the side wall itself.
The subject trench shoring assembly eliminates the sheering force which develops between the spreader device and the side walls by providing a different method of attaching the spreader device to the side wall.
In accordance with the subject invention, there is provided a trench shoring assembly of the type which includes a pair of spaced wall means interconnected by a connecting means with the wall means including a plurality of interconnected structural members which define a main frame. The connecting means includes a support means which is rigidly secured to the main frame and spreader devices. The support means is adapted to be connected to the spreader devices for transferring forces from the spreader devices directly to the main frame. The support means includes collar means and backing plate means. The collar means is adapted to be connected to the spreader devices and the backing plate means rigidly secures the collar means to the main frame whereby a force applied to the collar means is transferred to the backing plate means and, in turn, to the main frame.
A top member of the interconnected structural members extends longitudinally along the top of the wall means. The wall means includes ribbed members which extend perpendicularly to the top member and which are interconnected by a strip member intermediate the ends of the ribbed members.